cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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rtc.c (2603B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * arch/sh/boards/dreamcast/rtc.c
      4 *
      5 * Dreamcast AICA RTC routines.
      6 *
      7 * Copyright (c) 2001, 2002 M. R. Brown <mrbrown@0xd6.org>
      8 * Copyright (c) 2002 Paul Mundt <lethal@chaoticdreams.org>
      9 */
     10
     11#include <linux/time.h>
     12#include <linux/rtc.h>
     13#include <linux/io.h>
     14#include <linux/platform_device.h>
     15
     16/* The AICA RTC has an Epoch of 1/1/1950, so we must subtract 20 years (in
     17   seconds) to get the standard Unix Epoch when getting the time, and add
     18   20 years when setting the time. */
     19#define TWENTY_YEARS ((20 * 365LU + 5) * 86400)
     20
     21/* The AICA RTC is represented by a 32-bit seconds counter stored in 2 16-bit
     22   registers.*/
     23#define AICA_RTC_SECS_H		0xa0710000
     24#define AICA_RTC_SECS_L		0xa0710004
     25
     26/**
     27 * aica_rtc_gettimeofday - Get the time from the AICA RTC
     28 * @dev: the RTC device (ignored)
     29 * @tm: pointer to resulting RTC time structure
     30 *
     31 * Grabs the current RTC seconds counter and adjusts it to the Unix Epoch.
     32 */
     33static int aica_rtc_gettimeofday(struct device *dev, struct rtc_time *tm)
     34{
     35	unsigned long val1, val2;
     36	time64_t t;
     37
     38	do {
     39		val1 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) |
     40			(__raw_readl(AICA_RTC_SECS_L) & 0xffff);
     41
     42		val2 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) |
     43			(__raw_readl(AICA_RTC_SECS_L) & 0xffff);
     44	} while (val1 != val2);
     45
     46	/* normalize to 1970..2106 time range */
     47	t = (u32)(val1 - TWENTY_YEARS);
     48
     49	rtc_time64_to_tm(t, tm);
     50
     51	return 0;
     52}
     53
     54/**
     55 * aica_rtc_settimeofday - Set the AICA RTC to the current time
     56 * @dev: the RTC device (ignored)
     57 * @tm: pointer to new RTC time structure
     58 *
     59 * Adjusts the given @tv to the AICA Epoch and sets the RTC seconds counter.
     60 */
     61static int aica_rtc_settimeofday(struct device *dev, struct rtc_time *tm)
     62{
     63	unsigned long val1, val2;
     64	time64_t secs = rtc_tm_to_time64(tm);
     65	u32 adj = secs + TWENTY_YEARS;
     66
     67	do {
     68		__raw_writel((adj & 0xffff0000) >> 16, AICA_RTC_SECS_H);
     69		__raw_writel((adj & 0xffff), AICA_RTC_SECS_L);
     70
     71		val1 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) |
     72			(__raw_readl(AICA_RTC_SECS_L) & 0xffff);
     73
     74		val2 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) |
     75			(__raw_readl(AICA_RTC_SECS_L) & 0xffff);
     76	} while (val1 != val2);
     77
     78	return 0;
     79}
     80
     81static const struct rtc_class_ops rtc_generic_ops = {
     82	.read_time = aica_rtc_gettimeofday,
     83	.set_time = aica_rtc_settimeofday,
     84};
     85
     86static int __init aica_time_init(void)
     87{
     88	struct platform_device *pdev;
     89
     90	pdev = platform_device_register_data(NULL, "rtc-generic", -1,
     91					     &rtc_generic_ops,
     92					     sizeof(rtc_generic_ops));
     93
     94	return PTR_ERR_OR_ZERO(pdev);
     95}
     96arch_initcall(aica_time_init);